Last Updated on December 16, 2023 by Pittalks
If you’re a Harley Davidson owner or enthusiast, you’ve probably experienced or heard about the common issues related to Harley’s automatic primary chain tensioner. This comprehensive guide will provide you with detailed insights into this problem, its causes, and potential solutions.
What Problems Are Encountered With Harley’s Automatic Primary Chain Tensioner?
The Harley automatic primary chain tensioner, a safety device installed to maintain the right tension on the primary chain, can pose a series of problems when not functioning properly. Over-tightening of the chain can lead to premature wear and tear, irritating noises, power loss, and in extreme cases, severe engine damage.
Which Engines Are Affected?
Harley Davidson models fitted with the Evolution (Evo) engine, produced from 1984 to 1999, have been reported to experience issues with the automatic primary chain tensioner.
Which Models Specifically?
Specific models like the Touring Models, Dyna Glide Models, Softail Models, and Sportster Models equipped with the Evo engine have been reported to encounter these tensioner issues.
Twin Cam Engines
The Twin Cam engine models, introduced in 1999, weren’t immune to these tensioner problems either. These engines were designed to provide improved performance over the Evo engines but suffered from similar tensioner issues.
Evo and Twin Cam comparison:
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Which Models Specifically?
Various models fitted with the Twin Cam engine, including the LiveWire, Touring Models, Dyna Glide Models, Softail Models, Sportster Models, and Screamin Eagle CVO Models, have reported issues with the automatic primary chain tensioner.
Milwaukee 8 Engines
The latest engine in the Harley Davidson lineup, the Milwaukee 8, has been reported to face similar tensioner issues. Introduced in 2017, the Milwaukee 8 engine was engineered to offer improved performance, power, and fuel efficiency.
How doe the Milwaukee series and Twin Cam series stack up? The Harley 103 vs 107 Engine Showdown
Which Models Specifically?
Models such as the Touring Models, Softail Models, and Tri Glide equipped with the Milwaukee 8 engine have encountered issues with the automatic primary chain tensioner.
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What Are The Symptoms Of A Bad Primary Chain Tensioner?
If your motorcycle’s automatic primary chain tensioner is malfunctioning, you may notice unusual noise from the primary chain, increased vibration, poor engine performance, or in extreme cases, engine failure.
What Can Be Done About This?
Several aftermarket solutions are available to address the issue with the automatic primary chain tensioner. Many owners prefer to replace the factory-installed tensioner with an aftermarket manual tensioner, like the Baker Attitude Adjuster or the Hayden M6. These manual tensioners allow optimal adjustment of the chain’s tension, reducing the risk of over-tightening.
Is The Tensioner Adjustable?
The factory-installed automatic primary chain tensioner in Harley Davidson motorcycles is non-adjustable. It is designed to automatically adjust the primary chain’s tension based on the engine’s operating conditions. If you prefer an adjustable tensioner, you’d need to replace the automatic tensioner with an aftermarket manual tensioner. Then, you can take steps to adjust it yourself. Like so:
Primary Tensioner Upgrade Options
There are several upgrade options available for the primary chain tensioner. Popular options include the Baker Attitude Adjuster and the Hayden M6 manual tensioner. These manual tensioners allow for optimal adjustment, reducing the risk of over-tightening.
How Much Does It Cost To Replace The Primary Chain Tensioner?
The cost of replacing the primary chain tensioner can vary depending on the make and model of your motorcycle, the type of tensioner you choose, and whether you opt for professional service or a DIY approach. On average, you can expect to pay between $100 to $300 for an aftermarket manual tensioner, plus labor costs if you choose to have the work done by a professional.
Can You Replace The Tensioner By Yourself?
Yes, it’s possible to replace the primary chain tensioner yourself if you have some mechanical knowledge and the right tools. However, if you’re uncomfortable doing this kind of work yourself, it’s recommended to have the work done by a qualified technician.
What Happens If You Ignore The Issue? Can You?
Ignoring the issue with the automatic primary chain tensioner is not recommended. If the tensioner over-tightens the primary chain, it can lead to premature wear of the chain and bearings, reduced engine performance, and in severe cases, catastrophic engine damage. Therefore, if you suspect an issue with your tensioner, it’s crucial to address it as soon as possible.
Quick Overview of Important Points
The automatic primary chain tensioner on some Harley Davidson motorcycles has been reported to over-tighten the primary chain, which can lead to a range of issues. This problem has been reported on models with the Evo, Twin Cam, and Milwaukee 8 engines. Symptoms of a bad tensioner include unusual noise, increased vibration, poor engine performance, and engine failure. Solutions include replacing the automatic tensioner with an aftermarket manual tensioner, such as the Baker Attitude Adjuster or the Hayden M6.
The primary concern with Harley Davidson’s automatic primary chain tensioner is that it can apply excessive tension on the primary chain. This over-tensioning can lead to premature wear and tear of the chain and other related components, such as sprockets and bearings. It may also cause undue stress on the engine and transmission, potentially leading to more significant mechanical issues.
Reported issues with the automatic primary chain tensioner have been noted primarily in some Twin Cam engines, particularly those produced between 2006 and 2017. However, it’s important to note that not all models within this range may be affected, and owners should consult specific model information or a Harley Davidson technician for confirmation.
Signs of a malfunctioning primary chain tensioner on a Harley Davidson motorcycle may include unusual noises from the primary case, such as rattling or grinding sounds, especially at idle or low speeds. Excessive vibration and a noticeable change in the performance of the motorcycle can also be indicators. A definitive diagnosis typically requires inspection by a qualified technician.
The automatic primary chain tensioner issue can be a significant concern for Harley Davidson owners. However, by being informed and proactive, you can prevent potential damage and ensure the longevity and performance of your motorcycle.